A study of urinary immunoglobulins excretion after forced lordosis MASAKO MIHATA Department of Pediatrics, Hyogo College of Medicine, Hyogo, Japan (Director : Prof. Hiroyoshi Wada) Key word : orthostatic proteinuria, lordosis, urinary immunoglobulins excretion, low/non selective proteinurria Changes in the urinary excretion of immunoglobulins (IgG and IgA) before and after forced lordosis were studied in 26 children with orthostatic proteinuria (group OA, where proteinuria disappeared within 120 min after lordosis was referred to as group OAA and where if disappeared after more than 120 min was group OAB) and 9 children with chronic glomerulonephritis in the clinically stable state (group GN). Urinary immunoglobulins were measured by ELISA (enzymelinked immunosorbent assay). In resting urine, the urinary excretion rates (total protein, IgG, and IgA) and the urinary protein ratio (IgG/protein, IgA/protein, and IgA/IgG) did not significantly differ between groups OA and GN. When forced lordosis was carried out, at maximum protein excretion, the urinary IgA/IgG ratio in groups OAA and OAB were significantly decreased (from 198+44% to 17.3+12.9% and from 147+88% to 18.7+16.9%, respectively). The ratio of IgA/IgG in groups OAA and OAB was significantly lowerr than that in group GN (88.9+53.9%, pc 0.01). The urinary IgA/IgG ratio after lordosis in group OA was similar to the serum IgA/IgG ratio. These findings suggest that transient low or non-selective proteinuria after lordosis is a characteristic of orthostatic proteinuria. Analysis of the urine after forced lordosis, especially using the urinary IgA/IgG ratio at maximum protein excretion, may be an useful examination for differentiating OA from other glomerulonephritides.
Fig, 2a Standard curve and cross reaction of IgG. Fig, 2b Standard curce and cross reaction of IgA. Table 1 %CV of assay.
Fig. 3 Change of Protein, IgG, IgA excretion of lordosis. Protein : Total Protein excretion IgG : IgG excretion IgA : IgA excretion * P<0.05 Fig. 4 Changes of IgG/Protein, and IgA/Protein by lordosis.
Table 2 Comparison of IgA/IgG ratio between UM and serum. Fig. 5 Change of IgA/IgG by lordosis. Fig, 6 Comparison between group OAA1+OAB1 and group OAA2+OAB2.
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